You may have heard various people talk about HDR images. (WETA, Lucas, even Tim Sweeny). HDR images are part of a technology called HDRi which stands for "High Dynamic Range (image)". So... what on earth does that mean?

Here's a link to Wikipedia's article on the HDR format which I personally give all my credit to Paul Debevec for putting it to use for computer graphics purposes. Anyway, before you start trying to understand the usefulness of HDRi, please read the wikipedia link.

To sum up the excitement of HDR CG, think of it like the hype of the next-generation videogames that are about to come out, except set the stage for 1996 instead of 2006. Paul Debevec pioneered paralax mapping, HDR lighting, image-based modeling, his latest work includes some even more amazing technologies, and for the record he's my hero too.

To use HDRi images for 3D rendering, you need something called a light probe...

HDRI stands for High Dynamic Range Imaging, and is basically an image format that contains from the deepest shadow up to the brightest highlight information. While an 'ordinary' digital image contains only 8 bits of information per color (red, green, blue) which gives you 256 gradations per color, the HDR image format stores the 3 colors with floating point accuracy. Thus the 'depth' from dark to light per color is virtually unlimited. Using HDR images in a 3D environment will result in very realistic and convincing shadows, highlights and reflections. This is very important for realistic emulation of chrome for example.

Light Probe

A Light Probe is a HDR image containing 360 by 360 degrees (solid angle 4π steradians) image information. In other words : it's a 360 degree spherical panorama image, not only looking around the horizon, but also up and down. Thus a Light Probe image contains all visible information as can be seen from a specific point, wherever you turn your head.

Go to Properties tab and click the World button.In the World Section check the "Real Sky" Button

(optional)Go to "Ambient Occlusion" section and activate "Ambient Occlusion", then make sure "Raytrace" is chosen as gather method in Gather section"

(optional)Adjust quality settings:

Increasing number of samples reduces noise, but increases render times

Adaptive QMC is faster, but generates more noise than Constant QMC

In the Properties tab click Texture button->then click on 'show world texture'->then select type as 'image or movie'->then in mapping section select coordinates as 'Angmap'->then in in influence section uncheck the 'blend' button and check the 'horizon' button.

In the Image section click on open button and locate your HDR image and Load it.

In the "Texture and Input" tab, click "Add New" and "Angmap". Note that the Angmap button is the important thing to tell Blender that this file is a Light Probe file !

Then go to the "Map To" tab and deactivate "Blend" and activate "Hori".

Now go to the Texture settings (press F6) and change the "Texture Type" to "Image".

Click the "Load Image" button and locate your HDR image.

(optional step, as it was not needed for my setup :)

5. Press F10 and change the "Blender Internal" to "YafRay". You need to turn on Global Illumination and to set the quality to something other than "none". Note that the YafRay renderer does not come standard with the Blender installation. You need to download and install this separately.

Your result should look like this: (Rendering: left with Blender, right with YafRay) Click for larger version
Note that the reflecting ball reflects the whole interior from every angle, even though we added just a single image to the World settings !